The present invention relates to a disposable diaper adapted to absorb and retain human excretions and more particularly to such disposable diaper to be worn by babies, sick persons, aged people and persons suffering from incontinence, in which a selected portion of each flexible side flap incorporated with elastic band is turned upwards under the elastic effect of said elastic band.
Some of the absorptive articles such as disposable diapers have already adopted the side flaps constructed to be raised so that fitting of said side flaps around the thighs of the wearer is improved and thereby leakage of excretions which would otherwise occur across the thighs can be effectively avoided, for example, as disclosed in U.S. Pat. No. 4,579,556. In accordance with the technique as disclosed by this U.S. Patent, along the outer edges of the rectangular absorbent body (layer) interposed between or sandwiched by the topsheet and the backsheet, the side flaps rise under elastic effect of the elastic bands which are incorporated into the respective side flaps along the outer edges thereof. Such rising or turning up of the side flaps is believed to occur due to a fact that a rigidity of the absorbent body is higher than that of the side flaps and, as a consequence, the elastic effect of the elastic bands transmitted to said side flaps is blocked by the outer edge of said absorbent body and converted into an effect serving to turn said side flaps up.
According to this concept, however, the absorbent body is restricted to a configuration having the substantially linear outer edges, i.e., the rectangular form in general and its width is also restricted, so that it is difficult for the absorbent body to be configured in any other shape suitable to improve fitting of the diaper around the wearer's body, for example, in the form of a sandglass. In addition, although the side flaps are certainly turned up as has been described above, such rising or turning up is merely bending of the side flaps along the outer edges of the absorbent body. Accordingly, said side flaps might be subjected to a stress-strain due to the rigidity of said absorbent body and thereby their free flexibility might tend to be hindered, unless the height (width) of said flaps is dimensioned to be relatively large and distances between the elastic gathers formed by the associated elastic bands mounted on the free ends of the respective side flaps and the associated outer edges of said absorbent body are also dimensioned to be relatively large. At the same time, said absorbent body tends to be subjected to a stress-strain due to the elastic effect of said elastic bands and thereby to be irregularly deformed, resulting in various inconveniences such as deteriorated appearance of the diaper as being worn, an uncomfortability for the wearer and poor fitting of the diaper on the wearer's body, particularly a poor sealing effect around the thighs.
A typical technique to overcome the problems encountered when the side flaps including the elastic gathers formed by the elastic bands are associated with combining with a semi-rigid absorbent body is disclosed in the U.S. Pat. No. 3,860,003. The technique disclosed in this U.S. Patent teaches that, when the side flaps are incorporated with the elastic bands along the outer sides thereof sufficiently spaced from the associated outer edges of the absorbent body, an effective seal is obtained around the thighs without significantly hindered contractibility and flexibility of the side flaps by said elastic bands due to the rigidity of said absorbent body.
However, when the elastic bands are to be disposed along the outer sides of the side flaps sufficiently spaced from the associated outer edges of the absorbent body, it will be necessary that the width of the absorbent body is dimensioned to be relatively narrow at least in the crotch area. This will result in that a capacity or a volume to absorb and retain excretions is reduced in the most important area for this purpose and thereby leakage of excretions occurs across around the thighs. Although the U.S. Pat. No. 3,860,003 intends to eliminate the drawback of the prior art that the front portion of the diaper is encouraged to blossom or pouch outwards as though it were trying to form a damp apron, this intention will not be achieved when the respective elastic bands are sufficiently spaced from the associated outer edges of the absorbent body.
Thus, the prior art anticipates no measure to overcome the above-mentioned problems which are effectively solved, according to the present invention, by a particular arrangement of the side flaps as will be described in detail later.
A principal object of the present invention is, for the purpose of effectively overcoming the inconveniences as set forth above, to provide a disposable diaper so improved to achieve an effective seal around the thighs as can not be expected from the prior art and thereby to minimize a possible leakage of excretions across around the thighs.
Other objects and advantages of the present invention will be apparent from reading the following description.